Compressor unit



May 16, 1950 D c. HAGGARDT 2,508,253

COMPRESSOR UNIT i A i f5 i n gigi f Degr' CJ. Hoggordt INVENTOR.

ATTORNEY.

May 16, 1950 D. c. HAGGARDT 2,508,253

- COMPRESSOR UNIT Filed Sept. 26. v1946 2 Sheets-Sheet 2 I BYQ'UM@ ATTORNEY.

Patented May 16, 1950 Y UNITED STATES PATENT OFFICE COMPRESSOR UNIT Dean C. Haggardt, Denver, Colo.

Application September 26, 1946, Serial No. 699,528

11 Claims. (Cl. 230-181) This invention relatesV to new and useful improvements in compressor units.

` yOne object ofthe invention is to provide an improved compressor unit for compressing uids for use'inlrefrigerators, temperature contr-ol, air conditioning and similar or allied mechanisms.

An important vobject ofthe invention is to provide an improved compressor unit wherein the compressor andV its driving motor are lincorporatedin a single/assembly, ywhereby' a compact structure requiring a minimum space forinstallation is had and also whereby the unit includes a minimum number of working parts.

Ap'articular object of theinvention is to provide 'an improved unit, ofthe lcharacter described, wherein the' compressorV cylinder and its piston are mounted axiallyfwithin an electric driving motor, with improved' means for Acoupling the rotor of the motor' tothe compressor piston to impart reciprocation to said piston upon rotation of said rotor; `the cylinderv having. suitable yalved intake 1 and yexhaust ports' which communicate with the line or coil through which the'fluid to be'compressedis circulated, whereby operation of the motor actuates the compressor'piston to compress said fluid.

"f Aiurther objectof theinvention is to provide a combination compressor and motor unit which functions -as a two-stage compressor, whereby the fluid is rstfplaced under :pressure and is then nally compressed to the desired degree andrelcirculated? throughthe'refrigerating or other system; the two-stagecompression providing for more efdcient operation" at' less "operating costs and witha'minimum load `on Vthe compressor unit.

VStill another-object oi the invention'is to provideranlimproved device, of the character described, 'whereini the compressor piston element has' its opposite' ends? ofv differenti' cross-sectional areas whereby fone end functions asa piston of relatively large area ktodisplace a relatively large volume under-low pressure offluid and the oppositeend functions 'as a secondpiston of smaller area to'fdispla'ce relativelyesmallvolume under high? pressure of huid-with the ,result that each reciprocation of said piston -element. accomplishes a two-stage compressionofthe fluid.

'Another'objectof therinventi-on' is to provide an improvedV combination'- compressor andv motor unit, ofith'e".characterdescribed wherein the interior of the'casin'g `or housing of the `motor functions asa chamber `or reservoir for the 'luidduring the fir'ststage 'oircompression ofsaid iluid, therebyfeliminatingthe. necessity ofprovid-ing an auxiliary; chamber-for thisfgpurpose and permitting the unit to be extremely small and compact in construction and also permitting the fluid beingv compressed to act as a lubricant for the compressor piston element as it reciprocatesY in its cylinder.

The construction designed to carry out'theinvention will be hereinafter described together with other features of thefinvention.

The invention will be more readily understood from a reading ofthe following specication and by reference toy the accompanying drawing, Whereinan example ofthe invention is shown, and wherein:

Figure 1 is a longitudinal, vertical, sectional View of a compressor and motor unit, yconstructed in. accordance with the invention,

vFigure 2 is an enlarged, sectional view of the exhaust end ofthe Acompressor cylinder.

'Figure 3 is an enlarged, sectional view of the intake end of'said compressor cylinder,

Figure 4 is a transverse, vertical, sectional View, taken on the line 4`-4 of Figure 1,

Figure 5 is a transverse,vertical, sectional view, taken onthe line 5-5 of Figure 1, and

Figure 6 is an isometric View of the compressor piston.

In the' drawings, the numeral vIll'designates a casing or housing which is substantiallycylindrcal and which has its ends closed by end plates I I which are suitably bolted or otherwise secured thereto. VPacking gaskets I2 interposedbetween the endsof the housing and the end plates II seal 01T the joint therebetween. The housing I 0 is 'the casing or housing of an electric motorwhich includes a stator I3 mounted withinthe central portion'of said housing. `A double cylinder or tube vI 4: extends axially through vthe housing and' has its ends supported in suitable supportingflanged 'collars I5 which are bolted or otherwise secured to the inner surface of the -end plates. The'cylinder is Vnon-rotatable-within the housing. and forms a support orshaft on which the'rotor I6 of theelectric motor may rotate. As is clearly shownU in Figure 1 the vrotor includes a metal Vsleeve I1 which'is rotatable around the -cylinder I4 and suitable bearings I8 are interposed between the vsleeve and the outer surface of the cylinder 'tolfacilitate such rotation. The cylinder is-iormedwithan annular slotx20 at its central portion 4and an inwardly extending annular rib- 2| whichfis formed on the metal sleeve I'I lofytlle rotor is*v disposed within this slot to confine the sleeve 'and rotor-against longitudinal movement onthe cylinder.

The .main-bore 22 of the cylinder I4 is formed with a reduced portion 23,A whereby an internal to fit Within the first stage cylinder 22. The piston is formed with a reduced end B which is movable within thesecond stage cylinder 23 and the shoulder 26 formed on the piston is adapted to abut the shoulder 2libetween the cylinders in one extreme position of the piston.

` To impart a reciprocating movement to the pistori upon a rotation of the rotor l5, the piston is formed with a helical or spiral groove 2l in its exterior surface.V A ball member28 which is confined Within a radial opening 29 in the sleeve Il of the rotor has its lower surface engaged within the groove 2l, its upper surface being confined within the opening 29. The ball is retained in position by a suitable follower 3U. Rotation of the piston 25 is prevented by engagement of a radial pin or projection 3l which is secured within the wall of the cylinder i4 and 'which projects into a longitudinal groove or recess 32 provided in the external surface of said piston.

It will be apparent that the piston 25 is nonrotatable within the cylinders 22 and 23 and when rotation is imparted to the rotor i6 by operation of the electric motor, the co-action between the connecting ball 28 and the helical groove 21 will impart a reciprocating motion or movement to the double piston.V The helical groove is so disposed that complete reciprocation of the double piston will occur during one revolution of the rotor IBLv For admitting the fluid to be compressed to the intake end of the first stage cylinder 22, said cylinder is provided with an inlet opening 33. An inlet control valve 34 is mounted within this opening andhas the fluid inlet pipe 35 connected thereto. As is clearly shown in Figure 3 the valve 34 is constructed lso as to admit fluid into the cylinder but to prevent escape'of fluid from the cylinder back into the inlet pipe. Thus, upon the intake stroke of the piston which is a movement of the piston 25 to the left in Figure 1, the valve 34 will be opened by the suction created bythe piston and fluid will be drawn into the first stage of the cylinder.

Upon a reverse movement of the piston 25, that is, a movementto the right in Figure 1, the iiuid which has been drawn into the first stage cylinder will be discharged through an opening Y36 formed inthe end plate Il which closes the intake end of the piston. This opening has a check valve 31 which permits discharge of fluid from the cylinder but prevents entrance past said valve. A conductor 38 extends `from the opening 3(5,and through the closure end plate l l into the interior I of the housing l0. Thus, upon a movement of the piston to the right in Figure 1, the fluid is displaced through the conductor and into V thevinrterior of the housing. Because the first stage piston is relatively large, displacement of fluid from the cylinder through the conductor and into the housing Vwill be in relatively large volume and under a relatively low pressure.

Y The interior Vof the housing communicates through a conductor or pipe 39 and a vertical Vpassage 40 with the second stage cylinder 23. A

check valve 4l mounted in the passage 40 permits admission of fiuid into the second stage cylinder through the passage but prevents the fluid from flowing from the exhaust end of the cylinder back into the interior of the housing. Therefore, as the piston moves to the right in Figure 1, the reduced portion B of the piston creates a suction which will draw fluid from the interior of the housing into the 'exhaust end 23 of the second stage cylinder. It will be remembered that this fluid is under some pressure having been placed under pressure by the large end of the piston 25 in the first stage cylinder 22. As the piston reciprocates back to the left in Figure 1, the reduced end B of the piston forces the fluid from the exhaust end of the second stage cylinder outwardly past a valve 42 mounted in the end of said cylinder and into adischarge pipe 43 which is connected in the end plate ll. The valve 42 is a check valve type and allows discharge of uid from the cylinder While preventing admission into the cylinder from the pipe 43. It will be apparent that since the end B of the piston is relatively small in diameter and the cross-sectional area of the cylinder at the point is also relatively small, the fluid will be forced from the exhaust end of the second stage cylinder under a relatively high pressure and ata reduced volume. From the pipe 43, the compressed fluid is circulated through the refrigerating or other system with which the device is used.

The operation of the combined compressor and motor unit is believed obvious. Beginning the cycle with the parts shown in Figure 1, it will be apparent that as the rotor I6 rotates, the piston 25 will be moved toward the left in this gure. This movement will cause the smaller end B of the piston which forms the second stage piston to discharge the fluid under desired compression through the outlet 43, the discharge fluid having been drawn into vthe second stage cylinder upon thev preceding operation of the piston. As said piston moves to the left, the second stage piston discharges fluid under desired compression and the larger end of said piston forming the first stage piston creates a suction in the intake end of the first stage cylinder 22, whereby additional fluid is drawn through the inlet pipe 35 past the valve 34 into said intake end of the first stage cylinder.

Continued rotation of the rotor I6 causes the piston to reach the extremity of movement toward the left after which the piston moves back to the right in Figure 1; as this occurs, the fluid which has been drawn into the rst stage cylinder 22 is forced outwardly through the conductor 38 and into the interior of the housing. As explained, this displacement is of a relatively large volume and under some pressure so that this comprises a iirst stage of compression of the fluid. YAt the same time that iiuid is forced into the interior of the chamber through the conductor 38, additional fluid is drawn from the interior of the housing through the conductor 39 and vertical passage 40 into the second stage cylinder 23. This Vfluid which enters the second stage cylinder is under the pressure which the larger end of the piston has created and thus the fiuidis ready for the second stage of compression. This second stage is accomplished when the piston again moves back to the left in Figure 1 to begin the next'I cycle of operation.

The two-stage compression provides for exceptionally eflicient operation since the compression may be accomplished with less power. The

entire unit is simple and compact in construction, with the compressor unity being incorporated which is the double piston, inthe entire device ,and thacirculation of 'the fluid through fthe housing; 'whichforms a' first 'stage compression chamber allows the fluid to lubricate the piston and rotor. It is noted that the particular ball 28 which is used to transmit the reciprocating movement to the piston is employed because it minimizes friction; however, a radial pin would serve the same purpose. The valves that are shown are merely for the purposes of illustration and any suitable check valve device could be employed. The main feature of the invention is the two-stage compression which makes for maximum eiciency with minimum operating costs.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A compressorunit including, an electric motor comprising a sealed housing having a stator and a rotor therein, a compressor tube forming a pair of aligned cylinders which cylinders provide a first and second stage of compression extending axially through the rotor and having its ends supported in said housing and forming a support on which the rotor may rotate, a piston re'ciprocable within said cylinders, means for coupling the rotor to the piston whereby rotation of said rotor imparts reciprocation to the piston, a valved intake inlet at one end of the rst stage cylinder for admitting fluid to said cylinder, means for establishing communication between the cylinders, and a valved exhaust outlet at the exhaust end of the second stage cylinderfor discharging the fluid under compression.

2. AV compressor unit yas set forth in claim l, wherein the means for establishing communication between the cylinders is the interior of the motor housing and passages connecting the cylinders with said interior.

3. A compressor unit as set forth in claim 1, wherein the means for establishing communication between the cylinders is the interior of the motor housing and passages connecting the cylinders with said interior and valves mounted in said passages, whereby as the fluid is forced into the interior of the housing from the first stage cylinder it is placed under its initial stage of compression, the second stage of compression being completed when the fluid from the interior of the housing is discharged from the exhaust end of the second stage cylinder.

4. A compressor unit including, an electric motor comprising a sealed housing having a stator and arrotor therein, a compressor tube forming a first stage cylinder and a second stage cylinder extending axially through the rotor and having its ends supported in said housing, the tube forming a support on which the rotor may rotate, a piston reciprocable within said cylinders, means for coupling the rotor to the piston whereby rotation of said rotor imparts reciprocation to the piston, a valved inlet in the intake end of the first stage cylinder for admitting fluid into the cylinder, a passage extending from the rst stage cylinder to the interior of the motor housing whereby fluid from said cylinder is exhausted into thehpusing,` a secondpassage connecting the interior ofthe motor housing with the second stage `cylinder to admit fluid from said housing to that cylinder, and a valved discharge outlet leading fromthe second stage cylinder for discharging 'huid under compression from the cylinder.

5..A compressor Vunit as set forth in claim- 4, wherein vback-pressure kvalves are mounted in the passages connecting the interior of the housing and the cylinder ends, whereby flow in only one direction from the first stage cylinder, through the housing and into the second stage cylinder is possible.

6. A compressor unit as set forth in claim 1, wherein the bore of the compressor tube forming the second stage cylinder is reduced and also wherein the piston has a reduced portion reciprocable in said second stage cylinder, whereby the fluid displaced by that end of the piston operating within the second stage cylinder is greater in volume than that displaced by the other end of said piston.

7. A compressor unit as set forth in claim 1, wherein the means for coupling the rotor to the piston is a projection on the rotor and a helical groove on the exterior of the piston, together with co-acting means on the piston and cylinders for preventing rotation of the piston, whereby a rotation of said rotor assures reciprocation of the piston.

8. A compressor unit including, an electric motor comprising a sealed housing having a stator and a rotor therein, a compressor tube forming a first stage cylinder and a second stage cylinder and extending axially through the rotor with its ends supported in the housing, the cylinder forming a support on which the rotor may rotate, the cross-sectional area of the bore of the first stage cylinder being greater than the cross-sectional area of the second stage cylinder, a dual piston slidable within the cylinders and having a reduced end portion movable within the second stage cylinder, means for coupling the piston to the rotor whereby rotation of the rotor imparts reciprocation to the piston, a valved inlet for admitting fluid to the first stage cylinder, a chamber communicating with the outlet of the first stage cylinder, whereby fluid admitted to the cylinder is displaced into the chamber in a relatively large volume and under a relatively low pressure, means for establishing communication between the chamber and the second stage cylinder whereby the fluid from said chamber may be admitted to the cylinder, and a valve outlet connected to the exhaust end of said second stage cylinder, the displacement ofthe fluid from the second stage cylinder being under relatively greater pressure and lesser volume due to the reduced area of the cylinder and piston operable therein.

9. A compressor unit as set forth in claim 8, wherein the chamber is the interior of the motor housing which communicates with the ends of the cylinders through suitable flow passages.

10. A compressor unit as set forth in claim 8, wherein the chamber is the interior of the motor housing which communicates with the ends of the cylinders through suitable flow passages and check valves in said passages for permitting flow in one direction only, whereby the fluid is displaced from the first stage cylinder, through the interior of the housing, then to the second stage cylinder and nally discharged therefrom through the valved outlet.

11. A compressor unit as set forth in claim 8,

2,508,253 7 ,wherein the means for coupling the rotor to REFERENCES CITEDv the. piston is a projection-on the rotor and a The following references are of record in the hellcal groove on the exterlor of the p1ston, tome of this patent: getherwith cao-acting means on the piston and vcylinder for preventing rotation of the piston, 5 UNITED STATES PATENTS whereby a rotation of said rotor assures recipro- Number Name Date cation of the piston. 2,222,203 Manseau Nov. 19, 1940 DEAN C. HAGGARDT. 

